Remove duplicate LICENSE and NOTICE files from benchmark JARs

[kevinjqliu]

Similar to apache/iceberg#17406

These local JMH artifacts are not published, so releases are unaffected. Update their shade configuration to retain only the intended META-INF/LICENSE and META-INF/NOTICE, while preserving required attribution in those canonical files.

The shaded benchmark uber-JARs contain multiple LICENSE/NOTICE variants:

• parquet-benchmarks.jar
• parquet-plugins-benchmarks.jar

Reproduction

# Build all default and vector-plugin JARs without running tests.
./mvnw --batch-mode -Pvector-plugins -DskipTests clean package

# Check all final JARs; exclude only Maven Shade backup artifacts.
(
  failed=0
  while IFS= read -r -d '' jar; do
    licenses=$(jar tf "$jar" | grep -Eic '(^|/)LICENSE([._-].*)?$' || true)
    notices=$(jar tf "$jar" | grep -Eic '(^|/)NOTICE([._-].*)?$' || true)

    if [ "$licenses" -eq 1 ] && [ "$notices" -eq 1 ]; then
      echo "PASS: $jar"
    else
      echo "FAIL: $jar (LICENSE=$licenses, NOTICE=$notices)"
      jar tf "$jar" | grep -Ei '(^|/)(LICENSE|NOTICE)([._-].*)?$'
      failed=1
    fi
  done < <(
    # original-* JARs are temporary backups created by Maven Shade.
    find . -type f -path '*/target/*.jar' \
      ! -name 'original-*.jar' \
      -print0 | sort -z
  )
  exit "$failed"
)

Observed failures:

FAIL: ./parquet-benchmarks/target/parquet-benchmarks.jar (LICENSE=9, NOTICE=4)
FAIL: ./parquet-plugins/parquet-plugins-benchmarks/target/parquet-plugins-benchmarks.jar (LICENSE=4, NOTICE=3)

Expected: every final JAR contains exactly one LICENSE and one NOTICE file under META-INF/.